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0.17 You probably want more information about what you are in for. Fair enough. This book is a guided tour of contemporary metaphysics. That is why its title is This Is Metaphysics! Metaphysics is an important subfield of philosophy. Philosophy, like every academic discipline—anthropology, psychology, mathematics, comparative literature, physics, musicology, and so on—encompasses a wide variety of subfields, each of which focuses on a specific set of topics and issues. One way to understand what a discipline is up to is to look at its subfields, the questions pursued by the people working in those subfields, and the methods they use to pursue those questions. That’s basically the route that I take here. Philosophy has many subfields—too many for me to try to list, let alone describe, here—so, to narrow things down, I will focus on epistemology, logic, ethics, metaphysics, various philosophies of X, and the history of philosophy.

0.18 I’ll tell you a bit about the first three subfields of philosophy first. And I’ll mention how knowing a little about them is important when thinking about metaphysics. Then we’ll get to metaphysics. Finally, I’ll discuss some philosophies of X and the history of philosophy.

0.19 Epistemology is the subfield of philosophy that studies what makes knowledge different from mere true belief, what it is for something to be evidence for a belief, what kinds of evidence we have, and where those kinds of evidence come from. Suppose Fred believes that 2 + 2 = 5. Does he know that 2 + 2 = 5? Of course not, because in order to know something, the thing in question must be true. Suppose Ross believes that the love of his life is thinking about him right now because this is what his horoscope says. Suppose Ross’s belief is true—still he doesn’t know this because he doesn’t have good evidence for this belief. What kind of evidence would Ross need in order to know that the love of his life is thinking about him? Suppose Elizabeth knows that 2 + 2 = 4 and that the sky is blue. Is the kind of evidence she has for believing that 2 + 2 = 4 the same as the kind of evidence she has for believing that the sky is blue? Elizabeth knows that the sky is blue because she can see it with her own two eyes. Are the truths of mathematics known by perception in this way?

0.20 It’s hard to avoid thinking about epistemology when doing any other branch of philosophy. Whenever a philosopher makes a claim, it is natural to wonder what the evidence for that claim is. Once you have worked through this book on metaphysics, you will naturally start to wonder about the epistemology of metaphysics. In fact, some questions in the epistemology of metaphysics will be briefly discussed in Section 7.2.

0.21 Logic is the subfield of philosophy that studies what makes an argument a good argument. When philosophers use the term “argument,” they don’t mean something like the fight you have with your mom or dad when you can’t borrow the car. An argument is a sequence of claims, the last of which is supposed to follow from the previous ones. The last claim in an argument is the conclusion of that argument, and the claims that are supposed to provide support for that conclusion are the premises of that argument. Here is an example of an argument: “All pieces of cheese are delicious. This yellow cube is a piece of cheese. So, this yellow cube is delicious.” We’ll call this argument the cheese argument, since we’ll want to refer back to it in a minute.

0.22 LThere are two ways for an argument to fail. First, the premises of the argument could be false. Second, the premises of the argument could fail to support the conclusion of the argument, regardless of whether the premises are true.

0.23 LTo see the difference, consider the following arguments. Here’s the first argument:

“The moon is made of Parmesan cheese. If the moon is made of Parmesan cheese, then the moon is delicious. So, the moon is delicious.”

Call this argument the cheesy moon argument. The cheesy moon argument is clearly a silly argument because the first premise of the argument is false. But there is nothing wrong with the logic of the argument: if the premises were true, the conclusion would also be true. Contrast the cheesy moon argument with this argument, which we’ll call the dog argument:

“Kris McDaniel is a human being. Ranger McDaniel is a dog. So, Parmesan cheese is delicious.”

The premises of the dog argument are true—and so is the conclusion. But it is still a lousy argument, because the premises have nothing to do with the conclusion and they certainly do not in any way provide support for the conclusion. The logic of this argument is messed up.

0.24 LLogicians call an argument valid (this is a technical term!) when it is not possible for the argument to have all true premises and a false conclusion. The cheese argument and the cheesy moon argument are valid arguments in this technical sense. Logicians call an argument factually correct when all of its premises are true. The dog argument is not valid, but it is factually correct. Logicians call an argument sound when it is both valid and factually correct. Sound arguments are great!

0.25 LLogic is super important to all areas of philosophy, including metaphysics. Philosophical discussions typically proceed by evaluating arguments for interesting claims, and to do this you need to figure out whether the conclusion really follows from the premises.

0.26 LOk, let’s move on to the next subfield of philosophy. Ethics is the subfield of philosophy that is concerned with (among other things) the questions of what makes an action right or wrong, what makes a life a life worth living, and what character traits are admirable or despicable. Who hasn’t wondered about this stuff? One of the things we’ll discuss at the very end of the book (Section 7.5) is whether thinking about metaphysics can make our lives go better for us. In short, we’ll do a bit of the ethics of metaphysics.

0.27 LNow for metaphysics. Metaphysics is the philosophical study of reality. In a way, metaphysics is the least applied and most theoretical of the subfields discussed so far. Both ethics and epistemology concern themselves with what we should do and what we should believe, and the study of logic is super important for reasoning correctly. But metaphysics is a purely theoretical investigation of reality, and it is not directly practical in the way that ethics, epistemology, and logic are.

0.28 Metaphysics addresses questions that cannot be fully answered by empirical scientific investigation alone. This does not mean that empirical scientific investigation is never relevant to any metaphysical question. On the contrary, it frequently is. But empirical scientific investigation alone can’t fully answer metaphysical questions. Among the questions that metaphysics addresses are:

 Do we have free will?

 What is the nature of human persons—are we purely physical beings or do we have a non‐physical part or aspect?

 How is time different from space?

 Is everything a particular or are there universals?

 What is the nature of possibility and necessity?

Many of these questions will be discussed at length in the chapters to follow. For some of these questions, the connections to empirical science will be more obvious—such as the question of how time is different from space. For other questions, the connections will be less obvious. The metaphysician should not dogmatically assert that empirical science can shed no light on metaphysical questions. But it is also an equally open question whether empirical science always can. I recommend a “wait and see” attitude towards this question as you read through the book.

0.29 Time for some more subfields, so that you can get a clear sense of what philosophy is about and how metaphysics fits in with the rest of philosophy. Every aspect of our lives can generate philosophical questions, and this is why there exist the subfields of philosophy I am calling philosophies of X, such as the philosophy of religion, philosophy of science, philosophy of language, philosophy of sports, feminist philosophy, philosophy of art, and so on. Each of these subfields is unified by its focus on a particular X—but each of these subfields also overlaps in various interesting ways with epistemology, logic, ethics, and metaphysics. Consider, for example, one of the central questions in the philosophy of religion: Is there a God? This central question is also an important question in metaphysics, though it won’t be addressed in this book. Now consider the question of whether the testimony from various holy texts provides evidence for the existence of God. This is an important question in the philosophy of religion, but it also clearly connects with an important question in epistemology, namely, whether testimony provides good evidence for beliefs. Finally, consider the question of whether we have a moral obligation to worship God, provided that such a being exists. This is an important question in the philosophy of religion, but it is also a question that ethicists might ponder. Similar observations can be made about each of the various philosophies of X. The subfields of philosophy are not cleanly separated. Rather, in philosophy, every question leads to further questions.

0.30 Finally, there is the history of philosophy, which is devoted to the study of the history of various philosophers, their arguments, their views, and so on. There is an interesting philosophical question about the relation of the history of philosophy to the rest of philosophy: not many academic disciplines incorporate the study of the history of their discipline into their core curriculum. How relevant is the history of mathematics or the history of biology to the research of contemporary mathematicians or biologists? On the face of it, it is not very relevant at all, which is probably why there are few such classes taught in mathematics or biology departments, and, even when they are taught, they are rarely classes that one must take in order to complete one’s degree in that major. Yet in most departments in North America, not only is the history of philosophy taught but typically several classes in the history of philosophy are required in order to complete a philosophy major. Does this difference suggest that the history of philosophy is important to contemporary research in philosophy?

0.31 This is a hard question, I think. But regardless of what the correct answer to this question is, this will be a book focused on contemporary metaphysics, which means we will engage in very little historical reflection in what follows. Occasionally though, I will mention important figures in the history of philosophy when their views or arguments are relevant to the contemporary material I am discussing.

0.32 Hopefully this brief overview of the various subfields of philosophy and their relations to metaphysics will be useful for what follows. As I mentioned earlier, I’m going to do my best to make the journey as smooth as possible, but since philosophy is inherently tricky, you should expect to hit the occasional roadblock. You should also be prepared to never finish the journey: metaphysics rarely delivers definitive answers to the questions it asks. I do not expect to teach you the answer to any given metaphysical question, although I believe that there usually is a correct answer. Rather, what I hope to do is to teach you how to think carefully about metaphysical questions, and how to reason through arguments for metaphysical conclusions. Once you know what metaphysics is and how metaphysical inquiry is conducted, you are all set to do metaphysics on your own.

0.33 And this is important since metaphysical questions can be found anywhere. Here is an example that illustrates how quickly you can find oneself facing a metaphysical question, at least once you have been trained to see them. Suppose you are trying to decide on whether to invest in a soda pop company or in a computer company. Part of what you do when making this sort of decision is you ask yourself what would happen were you to select some course of action out of the options available to you. You think to yourself thoughts like, “If I were to do this, then that would happen, but if I were to do this other thing, then that other thing would happen.” In short, you contemplate what philosophers call counterfactuals, which are claims about what would happen if something else were to happen. And you are going to successfully deliberate about what to do only if you have some reason to think that these counterfactuals can be true. But now for the metaphysical question: What makes a counterfactual true? (We’ll have more to say about this question in Section 4.4.)

0.34 In general, metaphysical questions are lurking behind pretty much every corner. Having some insight into how to think about them might be a skill worth picking up. One of my goals is to help you develop that skill.

0.35 Although the title of the book is This Is Metaphysics, I don’t cover every topic that is discussed by metaphysicians. As I said a moment ago, metaphysical questions lurk behind every corner, and so it is unlikely that any book would cover every topic. Still, I want to be clear that there are important topics that metaphysicians do talk about that are not discussed in this book. My main reason for not discussing them is just that the goal of this book is not to cover every topic in metaphysics—if this were the goal, maybe the book would be titled This Is All of the Metaphysics—but rather to introduce you to the activity of doing metaphysics. An omission of these topics is not an admission of their unimportance. If, by working through this book, you develop the skills needed for thinking about metaphysics, you will be well prepared to think hard about these other topics as well.